Gasoline ignition control additives



GASOLINE IGNITION CONTROL ADDITIVES John A. Pianfetti, South Charleston,W. Va., and Gennady M. Kosolapotf, Auburn, Ala., assignors to FoodMachinery and Chemical Corporation, New York, N.Y., a corporation ofDelaware No Drawing. Application October 7, 1955 Serial No. 539,259

6 Claims. (Cl. 260-461) This invention relates to new compositions ofmatter, their novel preparation and their use as gasoline igni- F tioncontrol additives.

More particularly, this invention relates to organophosphor'o'uscompounds as new compositions of matter, their l novel preparation andtheir use as gasoline ignition control additives. l The need forimproved gasolines has been spurred since the end of World War II by theautomotive industrys race to produce more and more powerful internalcombustion engines. To achieve this greater horsepower, engine manufacturers have steadily increased cylinder compression ratios to thepoint where they now average 7.5 to 1. One of the factors necessary toachieve maximum operating efiiciency from these high compression enginesis that the ignition of the fuel-air mixture takes place at the momentof greatest compression.

As engines become more powerful, they demand higher octane fuel whichcan be manufactured only with an increase in the tetra-alkyl leadcontent. The use of these organic lead compounds in gasolines leads tothe formation, during combustion, of lead salts which catalyze theoxidation of the carbonaceous residues from the fuel and oil and lowerthe ignition temperature of the carbon residues thus creating glowingparticles that ignite the fuelair charge prematurely.

It has been the practice of the art to add to fuels containing organiclead compounds, a halohydrocarbon for the purpose of converting the leadinto lead halides volatile at the combustion temperature of the gaswithin the cylinder and which lead compound would be swept out with theexhaust gases.v These compounds are known as scavengers. In actualpractice, however, the formation of lead oxyhalides and lead oxides aswell as the volatile lead halides cannot be avoided and deposits of leadcompounds are found in the combustion chamber even when such scavengersare employed.

It is an object of the instant invention to provide new compositions ofmatter which may be employed as gasoline additives. It is another objectof this invention to provide new compositions ofmatter which will aid inthe suppression of the pre-ignition characteristics of the fuelai'rmixture. It is a further object of this invention to provide novel meansfor preparing these new compositions of matter. Further objects willappear as a description l of this invention unfolds.

We have discovered certain organophosphorous compounds having propertieswhich render them suitable for use as pre-ignition control additives. Ithas been found that the defect of pre-ignition arising from the use ofconventional leaded gasolines can be substantially lessened by the useof the compounds of this invention. These organophosphorous compoundsappear to function by conve'rting the lead present in the fuel into'leadcompounds having a very low catalytic. eifect in reducing the ignitiontemperature of thecarbon deposits within the combustion chamber ascompared to, the lead compounds .that form in.-

the 'bombus'tion chamber, absent the 'organophos'phorouk Patented Apr.7, 1959 2 compounds of this invention. Thus, an increase in the ignitiontemperature of the cylinder deposit would likewise decrease the tendencyof the deposit to pro-ignite the fuel-air mixture.

The terms, ignition temperature and glow point, are meant to besynonymous for the purposes of this specification unless a contraryintention is shown.

The organophosphorous compounds which we have discovered as suitable foruse in accordance with this invention are: a

(1) Halogenated esters of phosphonous acid in which R may be a hydrogen,an aliphatic chain up to and including six carbon members, a phenyl orsubstituted phenyl radical, X may be a member of the halogen group and Ymay be an aliphatic chain up to and including six carbon members, anaryl or a substituted aryl radical.

(2) Halogenated thio esters of primary phosphonic acids H IRCH-CHaOPOCHz-CHR in which R may be a hydrogen, an aliphatic chain up toand including six carbon members, a phenyl or substituted phenylradical, X may be a member of the halogen group and Y may be analiphatic chain up to and including six, carbon members, an aryl or asubstituted aryl radical.

These new compounds, both the halogenated esters of phosphonous acid andthe halogenated thio esters of phosphonic acid, were prepared in a novelmanner.

. The novel manner of preparing the halogenated esters of phosphonousacid is through the reaction of dihalophosphines and oxiranes orsubstituted oxiranes.

The term oxirane is used to designate the grouping,

hence,

CHsCH-CH2 is known as methyl oxirane. This compound is also I known aspropylene oxide.

The aliphatic and aromatic dihalophosphines may be prepared by heatingphosphorus trihalide with the corre: sponding dialkylmercury ordiarylmercury derivatives in sealed tubes for several hours at to 230C., as described in the literature. p

The examples that follow illustrate the novel prepara- I tion of thehaloesters of phosphonous acid.

EXAMPLE 1 and a calibrated addition funnel.

The flask was charged with 179 parts of phenyl dichloro phosphine. Fromthe calibrated addition funnel was added 116 parts of methyl oxirane(propylene oxide).

The oxirane was added over a period of an hour while. maintaining thetemperature of the reaction mass at about,

25 C. Upon completing the addition of the oxirane, the pressure in thesystem was reduced for a short-: interval .1 me tqzm t Ha d .to ea r m-Pi unreacted oxirane.

The product, bis(chloropropyl) phenyl phosphonite, obtained in nearquantitative yield had a specific gravity of 1.180 35/4 and a refractiveindex of 1.5308, D/25.

Calculated for C H O PCI P=10.5%, Cl=24.1%. Found: P=.2%', Cl=23.4%

EXAMPLE 2 The apparatus used for this experiment was the sameaszdescriibedin Example 1..

The flask was charged with. 117" parts of methyl dichlorophosphinet.From: the calibrated additionfunnel was added: l=16 parts of methyloxirane propylene oxide).

The: oxirane: was: added. over a period of an hour while maintaining thetemperature of the reaction mass at about 25 C. Upon completing theaddition of the oxirane, the pressure in the system was reduced for ashort interval of time to 2 mm. Hg in order to remove any traces ofunreacted oxirane.

The product, bis(chloropropyl) methyl phosphonite, obtained in nearquantitative yield, had a specific gravity of 1.137 35/4 C. and arefractive index of 1.4638 D/25 C.

Calculated for C H O PCl P=13.3%-, Cl=30.4%. Found: P=12.9%, Cl=29.6%.

The novel method of preparing the halogenated thionoesters of primaryphosphonic acids is by the reaction of the halogenated esters of.phosphonous acid and. sulphur toyield the appropriate thionophosphonate.

The examples that follow illustrate the novel preparation of thehalogenated thionoesters of phosphonic acid.

EXAMPLE 3 The apparatus used for this experiment was a 3-necked flaskfitted with a stirrer, thermowell and a reflux condenser.

The flask was charged with 132 parts of bis(chloropropyl)- phenylphosphonite. After heating the phosphonite to about 80 C., 15 parts ofsulphur were added slowly over a 30 minute period while keeping thetemperature at about 80 C. This temperature was maintained until but atrace of sulphur remained. The product was cooled, and filtered. Theproduct, bis(chloropropyl) phenyl thionophosphonate obtained in nearquantitative yield, had a specific gravity of 1.237 35/4 C. and arefractive index of 1.5451 D/25 C.

Calculated for C H O PSCl P=9.5%, Cl=21.7%, S=9.8%. Found: P=9.1%,Cl=21.5%, S=9.8%.

EXAMPLE 4 The apparatus used for this experiment was the same asdescribed in Example 3.

The flask was charged with 105 parts of bis(chloropropyl) methylphosphonite. After heating the phosphonite to about 80 C., 15 parts ofsulphur were added slowly over a 30 minute period while keeping thetemperature at about 80 C. This temperature was maintained until all buta trace of sulphur remained. The product was cooled, and filtered.

The product, bis(chloropropyl) methyl thionophosphonate, obtained innear quantitative yield had a specific gravity of 1.220 35/4 C. and arefractive index of 1.4933 D/25" C.

Calculated for C7H15OgPSC12: P=1l.7%, Cl=26.8%, S=12.1%. Found: P=11.3%,Cl=26.5%, S=12.1%.

The reaction between the dihalophosphine and oxirane may be conducted attemperatures below the preferred temperature of 40 C. The maximumtemperature of reaction is that at which rearrangement of productoccurs.

The reaction between the dihalophosphine and oxirane may be run at suborsuper-atmospheric pressure but for convenience it is preferable tooperate at atmospheric pressure.

An inert gas, such as, carbon dioxide or nitrogen, may

b the Sy em, d ring the though it is not necessary to the practice ofthis invention that an inert atmosphere be maintained during thereaction of the dihalophosphine and oxirane.

The conversion of the haloester of phosphonous acid to the halogenatedthio ester of a primary phosphonic acid by the addition of sulphur tothe former may be run over a wide temperature range though it ispreferable to maintain the reaction temperature at about C.

Preliminary testing of these compounds as pre-ignition additivesinvolved the common gasoline. acceptance tests including: solubility ofcompound in gasoline, water tolerance, gum formation and coppercorrosion- The first test, gasoline solubility, was conducted todetermine at least qualitatively whether the organophosphorus compoundswere soluble in gasoline. This determination was made by measuring thelight transmittancy of the gasoline both with and without the additionof the organophosphorus compound.

Solutions which contained 0.03 volume percent of the phosphoruscompounds were prepared by adding 0.03 ml. of the compound to ml. of apremium gasoline. After a short. shaking and standing period thesolution was transferred to an optical cell and the light transmittanceof the solution measured. This value was compared to the value for thepremium gasoline which did not contain an additive. A decrease in thelight transmittance of the base fuel of 1% or more indicates that theadditive is sufliciently soluble for the purposes of this: invention.

The water tolerance was determined by following the procedure detailedin ASTM D1094-52.

The gum formation was determined by employing the copper dish method setforth in ASTM D910-52T, Section 9].

The copper corrosiontest was conductedin accordance with theinstructions stated in ASTM D-53T.

The results of the above tests are tabulated in Table I.

Illustrative of the compounds tested are bis(chloropropyl) methylphosphonite, BCPMP; bis(chloropropyl) phenyl phosphonite, BCPPP;bis(chloropropyl) methyl thionophosphonate, BCPMTP; and tricresylphosphate, TCP;

The inclusion of the compound, tricresyl phosphate, in the tables of theinstant specification is for the purpose of comparing the compounds ofthe instant invention with that of a known gasoline pro-ignitionadditive.

Table I shows the compounds of the instant invention tobe compatiblewith gasoline in so far as. the common acceptance tests are concerned.

The low-gurn formation. of the compounds of the in.- stant inventionmake them particularly suitable as. additives for internal combustionengines.

Compounds found satisfactory as: regards the common. gasoline acceptancetests. were then, evaluated as preignition depressants.

A method, familiar to those skill'ed'inthe armor-deter mining a"compounds ability' to reduce the pre-ignitimrv characteristics of agasoline, is' the oven-test method. Broadly stated, this procedureentails placing known amounts of synthetic engine deposit in a Pyrexheating; boat, with orwi'thouti the pie-ignition. depressant added, nd:having a means for measuring the temperature-attire- 5 oven and thetemperature is increased at a uniform rate. The degree of temperatureresulting from a sudden/increase in temperature is taken as the glowpoint of the deposit.

The detailed method employed in determining the glow point of thecompounds of this invention is set forth below.

A synthetic engine deposit which contained 38.3 lead sulfate, 33.1% leadoxide, 7.7% lead chloride, 5.9% lead bromide and 15.0% carbon black wasprepared by adding the approximate amounts of the compounds together andmixing in a mortar and pestle. To a Pyrex Petrie dish, in. high and /2in. in diameter was added 0.40 g.:0.1 g. of the synthetic deposit. Overthis was burned in 100 ml. portions, gasoline which contained 0.03volume percent of the different organophosphorus compounds. The amountof additive used was dependent on the phosphorus content of theorganophosphorus compound. Enough phosphorus was used to theoreticallyconvert all the lead in the synthetic deposit to lead phosphate. Air wasintroduced into the gasoline during the burning operation at 2500 cc. aminute in an attempt to convert some of the carbon given off duringburning to oxides of carbon. An iron-constant in thermocouple was alsoplaced in the burning fuel in order to obtain some idea as to thetemperatures that occurred in the burning step. The majority of thegasoline burned between 150-200" C. and the end gases, approximately540%, burned between 350 and 450 C. After burning was finished thedeposit was scraped from the bottom and the inside wall of the dish andthis material then mixed in a mortar and pestle. A glow pointdetermination was then made on the treated deposit.

The apparatus for measuring the glow point consisted of a copper block,3 in. in length by 2 in. in diameter. A A in. wide collar was at one endof the block. Two vertical holes, 2.5 in. long and cm. in diameter weredrilled in the block. The block was heated by a 9 in. by 8 in. electricheating shell which was encased in aluminum. The deposit was placed in aPyrex heating boat which was 1 in. tall and 10 cm. in diameter. Air wasmetered through a rotameter and jetted onto the deposit through a steelhypodermic needle. The needle extended 2% inches inside the drilledhole. The temperature was found by means of a Chromel-Alumelthermocouple, which extended into the deposit.

In a typical experiment 0.2 g. of deposit was placed in a Pyrex boat andpacked lightly into the Pyrex container. The thermocouple was placed inthe deposit and air introduced at the rate of 200 cc./min. The variacwhich controlled the heating rate was set at 80 volts and was kept atthis reading through the experiment. Temperature readings were takenevery 10 minutes until 40 minutes had elapsed. After 40 minutes readingswere taken in 0.5 or 1.0 minute intervals, and the degree centigraderesulting from a sudden increase in temperature was taken as the glowpoint of the deposit. Table II lists the average glow point of depositscontaining compounds of this invention.

Table II Additive: Average glow point, C. BCPMP 320 BCPPP 325 BCPMTP 324TCP 327 None 309 the dibromotoluenes. Mixtures of these halohydrocar- Itis desirable that the combined organophosphorus and halohydrocarbonscontain not more than about by weight of the halohydrocarbons.

1 ,In general, the quantity of additives required in the fuel.

is that necessary to convert (theoretically) all the lead present astetraalkyl lead into the corresponding lead halide and lead salt of thephosphonite or thionophosphonate concerned. Such a quantity is usuallyreferred to as 1 theory. Greater or smaller quantities may be employedin some circumstances depending upon the particular components of thefuel and the type of engine in which it is intended to be used. In factone of the merits of the present invention is that it allows greatervariation in the quantity of additive employed than is permissible whena halohydrocarbon is used as the sole additive. Even small excesses ofhalohydrocarbon additives are detrimental in such circumstances whereaswith the additives of this invention a substantial excess can betolerated without adverse results. The preferred range of total additivecontent of the fuel is from 0.9 to 1.2 theories.

Both the fuels and the compositions suitable for addition to fuelsprovided by this invention may advantageously contain further compoundsknown to exert a stabilizing and/or antioxidizing effect on hydrocarbonsof the gasoline boiling range. In this connection, 2,4-dimethyl-6-tertiary butyl phenol is a particularly useful additive, other compoundssuch as hydroquinone, 2,6-ditertiary-butyl-4- methyl phenol,N-phenyl-u-naphthylamine and N,N- dibutyl-p-phenylenediamine may beemployed.

The fuels of this invention may be compounded by simply mixing theingredients in any order. Thus the organophosphorus additive may beadded to a leaded gasoline which already contains a halohydrocarbonadditive. Alternatively, the organophosphorus may be incorporated in atetra-alkyl lead fluid containing a halohydrocarbon additive and wholecomposition blended into the fuel. Again the organo-phosphorus additivemay be added to an unleaded gasoline and the tetra-alkyl lead fluidcontaining a halohydrocarbon scavenger added subsequently.

Pursuant to the requirements of the patent statutes, the principle ofthis invention has been explained and exemplified in a manner so that itcan be readily practiced by those skilled in the art, suchexemplification including what is considered to represent the bestembodiment of the invention. However, it should be clearly understoodthat, within the scope of the appended claims, the invention may bepracticed by those skilled in the art, and having the benefit of thisdisclosure, otherwise than as specically described and exemplied herein.

That which is claimed as patentably novel is:

11. A composition of matter represented by the formu a:

in which R is selected from the group consisting of hydrogen and loweralkyl and phenyl radicals; Y is selected from the group consisting oflower alkyl and phenyl radicals and n is an integer from 1 to 2inclusive.

2. As a new composition of matter, bis(betachloropropy1)methylphosphonite.

3. As a new composition of matter, bis(betachloropropyl)phenylphosphonite.

4. As a new composition of matter, bis(betchloroprov ply)methylthionophosphonate.

7 5. A method of preparing the halogenated thionoesters of primaryphosphonic acids of the formula OOHzCHC1-R s--Y o-cH20B1oL-R.

of primary phosphonic acids in accordance with claim 5, in which thehaloester of phosphonousacid is bis(betachloropropy1)methyl phosphonite.

References Cited in the file of this patent UNITED STATES PATENTSCampbell Aug. 13, 1946 Withrow Sept. 9, 1947 Teeters Ian. 25, 1949Ballard et a1 Sept. 2-2, 1953 OTHER REFERENCES Kosolapofl: OrganoPhosphorus Compounds, page 185 1950), John Wiley & Sons, Inc., New York,NY.

1. A COMPOSITION OF MATTER REPRESENTED BY THE FORMULA:
 5. A METHOD OFPREPARING THE HALOGENATED THIONO ESTERS OF PRIMARY PHOSPHONIC ACIDS OFTHE FORMULA